Unclear error message for pointer types in pattern matching

unsafe class C
{
    static void Main()
    {
        int* ptr = null;
        _ = ptr is var (x); // error CS8521: Pattern-matching is not permitted for pointer types.
        _ = ptr is var y; // valid code
    }
}

The error message shown above doesn't mention anything about parenthesized patterns, despite the fact that that's the only difference between those two lines. We can make this clearer.